Liquid fuel atomizer

ABSTRACT

An atomizer for atomizing liquid fuels for combustion consisting of an outer, annular liquid nozzle chamber which converges towards an annular outlet therefrom and a coaxial, inner gas nozzle chamber which converges towards an annular outlet therefrom. A rigid annular deflector member is positioned coaxially with respect to the outlet openings and extends at least from the outlet openings to a position downstream of such openings. The deflector member also has a gas bleed duct leading to a further deflector arranged so as to deflect a gas stream across the outer end face of the deflector member.

Cresswell Dec. 2,1975

LIQUID FUEL ATOMIZER v [75] Inventor: Alan Cresswell, Rochester, Englandf' bxamlrfer Roben Asslstant E.rammerAndres Kashmkow Asslgneei DecafixLimited, Rochester. Attorney, Agent, or FirmLowe, King & Price England[22] Filed: Oct. 25, 1974 21] Appl. No.: 518,094 ABSTRACT An atomizerfor atomizing liquid fuels for combustion [30] Forelgn Apphcat'on PnontyData consisting of an outer, annular liquid nozzle chamber Oct. 26, 1973nited K gd m 49 /7 which converges towards .an annular outlet therefromand a coaxial, inner gas nozzle chamber which conl 239/4193; 239/424;verges towards an annular outlet therefrom. A rigid 7 239/4 239/500annular deflector member is positioned coaxially with H IL (1 B05B15/02; 30513 BOSB 1/2 respect to the outlet openings and extends atleast Field Of Search from the outlet openings to a position downstreamof 239/424, 6, 432, 433, 500, 461 such openings. The deflector memberalso has a gas bleed duct leading to a further deflector arranged soReferences Cited as to deflect a gas stream across the outer end face ofUNITED STATES PATENTS the eflector member.

3,093,314 6/1963 Meyer 239/433 X FOREIGN P-ATENTS OR APPLICATIONS 5 1Draw 1,020,942 2/1953 France 239/422 Ml rm \llllllll' U.S. Patent Dec.2, 1975 3,923,248

LIQUID FUEL ATOMIZER The invention relates to atomizer, moreparticularly for atomizing liquid fuels for combustion.

According to one aspect of the invention an atomizer consists solely ofan outer, annular liquid nozzle chamber which converges towards anannular outlet therefrom, a coaxial, inner gas nozzle chamber whichconverges towards an annular outlet therefrom and a rigid annulardeflector member positioned coaxially with respect to said outletopenings and extending at least from said outlet openings to a pointdownstream of said outlet openings, the deflector member also having agas bleed duct leading to a further deflector arranged, in use, todeflect a gas stream across the outer end face of the deflector member.

Preferably the gas bleed duct and arrangement of further deflectors aresuch as to provide said gas stream at approximately one third of theoperating gas pressure of the atomizer.

The diameter of the further deflector may be approximately one half thediameter of the outer end face of the deflector member.

The further deflector may comprise an insert which is mounted in acentral aperture in the deflector member and may be spaced between 0.004and 0.007 inches from the outer end face of the deflector member.

The foregoing and further features of the invention may be more readilyunderstood from the following description of a preferred embodimentthereof, by way of example, with reference to the accompanying drawing,which is a perspective view, part cut away, of an atomizer.

Referring now to the drawing there is shown an atom izer which comprisesa distributor member 11 formed with an outer circumferential ring ofaxial liquid feed passages 12 and an inner circumferential ring of axialgas feed passages 13. An inner surface 14 of member 11 is screw threadedto receive a coaxial feed pipe (not shown) to supply gas to passages 13and liquid to passages 12 with ring seals 15 and 16 interposedtherebetween.

The gas feed passages 13 lead into a convergent annular nozzle chamber17 which is defined by a frustoconical divergent surface 18a of adeflector member 18 which is screw threaded into a central aperture inthe distributor member 11 at the end remote from the feed thereto.

The liquid feed passages 12 lead into a convergent annular nozzlechamber 19 formed by a cylindrical extension lla and the innerfrusto-conical convergent surface 200 of an annular member 20 which isscrew threadedly engaged with the outer surface of member 11.

A further deflector 21 is screw threadedly engaged in a central aperturein deflector member 18 so as to have a central axial passage 22 inregistry with a central axial through passage 23 of deflector member 18.The further deflector 21 is also formed with radial metering passages 24leading from passage 22 to an annular space 25 between members 18 and21. The inner surface of the outer portion of further deflector 21 isarranged to be spaced from the outer surface of deflector member 18 bybetween 0.004 and 0.007 inches. The diameter of the outer portion offurther deflector 21 is arranged to be approximately one half thediameter of the outer surface of deflector member 18.

In operation compressed gas is fed through feed passages 13 to chamber17 where it is emitted at sonic velocity to flow along the outer surfaceof deflector member 18. As the pressure of the gas decreases alongdeflector member 18 its velocity increases to supersonic. When the gasapproaches the curved portion of deflector member 18 the gas pressureincreases and the velocity decreases so producing shock waves. Liquid tobe atomized is fed through passages 12 to chamber 19 and then is emittedas a film into the gas being emitted from chamber 17. The liquid film isaccelerated by the gas and maintained out of contact with deflectormember 18 by the gas so effectively forming a divergent nozzle betweendeflector member 18 and the liquid film. The acceleration of the liquidfilm reduces its thickness and causes shearing. The pressurefluctuations at the culmination of the supersonic velocities reached bythe gas which produce the shock waves cause vibrations of the liquidlayerand further shearing and break up occurs in a plane normal to thehorizontal shearing.

Gas is also fed through passages 23, 22 and 24 respectively into annularspace 25 and thence between member 21 and 18 to provide a continuous gasstream across the face of deflector member 18. The size of meteringpassages 24 and the location of member 21 are arranged to be such thatthe gas pressure of the stream is approximately one third of theoperating gas pressure of the atomizer.

This gas stream applied across the face of deflector member 18 forms nopart of the atomization process but prevents build up of carbon or otherdeposits on the face of deflector member 18 when the atomizer is beingused in a fuel firing operation. Without the provision of the furtherdelfector 21 the deposits could build up to project beyond the peripheryof member 18 and impair the operating efficiency thereof.

I claim:

1. An atomizer comprising an outer, annular liquid nozzle chamber whichconverges towards an annular outlet therefrom, a coaxial, inner gasnozzle chamber which converges towards an annular outlet therefrom, arigid annular deflector member positioned coaxially with respect to saidoutlet openings and extending at least from said outlet openings to apoint downstream of said outlet openings, a further deflector arrangedspaced apart from and coplanar with the outer end surface of thedeflector member and a gas bleed duct formed in the deflector member soas to lead from a gas supply duct to the space between the deflectormember and further deflector member.

2. An atomizer as claimed in claim 1 wherein the gas bleed duct andarrangement of further deflector are such as to provide said gas streamat approximately one third of the operating gas pressure of theatomizer.

3. An atomizer as claimed in claim 1 wherein the diameter of the furtherdeflector is approximately one half of the diameter of the outer endface of the deflector member.

4. An atomizer as claimed in claim 1 wherein the further deflectorcomprises an insert which is mounted in a central aperture in thedeflector member.

5. An atomizer as claimed in claim 1 wherein the further deflector isspaced between 0.004 and 0.007 inches from the outer end face of thedeflector member.

1. An atomizer comprising an outer, annular liquid nozzle chamber whichconverges towards an annular outlet therefrom, a coaxial, inner gasnozzle chamber which converges towards an annular outlet therefrom, arigid annular deflector member positioned coaxially with respect to saidoutlet openings and extending at least from said outlet openings to apoint downstream of said outlet openings, a further deflector arrangedspaced apart from and coplanar with the outer end surface of thedeflector member and a gas bleed duct formed in the deflector member soas to lead from a gas supply duct to the space between the deflectormember and further deflector member.
 2. An atomizer as claimed in claim1 wherein the gas bleed duct and arrangement of further deflector aresuch as to provide said gas stream at approximately one third of theoperating gas pressure of the atomizer.
 3. An atomizer as claimed inclaim 1 wherein the diameter of the further deflector is approximatelyone half of the diameter of the outer end face of the deflector member.4. An atomizer as claimed in claim 1 wherein the further deflectorcomprises an insert which is mounted in a central aperture in thedeflector member.
 5. An atomizer as claimed in claim 1 wherein thefurther deflector is spaced between 0.004 and 0.007 inches from theouter end face of the deflector member.